Choose reasonable "smart" times to display for transactions

Logic:
- If sending a transaction, assign its timestamp to the current time.
- If receiving a transaction outside a block, assign its timestamp to the current time.
- If receiving a block with a future timestamp, assign all its (not already known) transactions' timestamps to the current time.
- If receiving a block with a past timestamp, before the most recent known transaction (that we care about), assign all its (not already known) transactions' timestamps to the same timestamp as that most-recent-known transaction.
- If receiving a block with a past timestamp, but after the most recent known transaction, assign all its (not already known) transactions' timestamps to the block time.

src/wallet.h

@@ -17,6 +17,7 @@
 #include "ui_interface.h"
 #include "util.h"
 
+class CAccountingEntry;
 class CWalletTx;
 class CReserveKey;
 class CWalletDB;
@@ -143,6 +144,10 @@ public:
     bool ChangeWalletPassphrase(const SecureString& strOldWalletPassphrase, const SecureString& strNewWalletPassphrase);
     bool EncryptWallet(const SecureString& strWalletPassphrase);
 
+    typedef std::pair<CWalletTx*, CAccountingEntry*> TxPair;
+    typedef std::multimap<int64, TxPair > TxItems;
+    TxItems OrderedTxItems(std::string strAccount = "");
+
     void MarkDirty();
     bool AddToWallet(const CWalletTx& wtxIn);
     bool AddToWalletIfInvolvingMe(const CTransaction& tx, const CBlock* pblock, bool fUpdate = false, bool fFindBlock = false);
@@ -351,6 +356,7 @@ public:
     std::vector<std::pair<std::string, std::string> > vOrderForm;
     unsigned int fTimeReceivedIsTxTime;
     unsigned int nTimeReceived;  // time received by this node
+    unsigned int nTimeSmart;
     char fFromMe;
     std::string strFromAccount;
     std::vector<char> vfSpent; // which outputs are already spent
@@ -394,6 +400,7 @@ public:
         vOrderForm.clear();
         fTimeReceivedIsTxTime = false;
         nTimeReceived = 0;
+        nTimeSmart = 0;
         fFromMe = false;
         strFromAccount.clear();
         vfSpent.clear();
@@ -429,6 +436,9 @@ public:
             pthis->mapValue["spent"] = str;
 
             WriteOrderPos(pthis->nOrderPos, pthis->mapValue);
+
+            if (nTimeSmart)
+                pthis->mapValue["timesmart"] = strprintf("%u", nTimeSmart);
         }
 
         nSerSize += SerReadWrite(s, *(CMerkleTx*)this, nType, nVersion,ser_action);
@@ -449,15 +459,17 @@ public:
                     pthis->vfSpent.push_back(c != '0');
             else
                 pthis->vfSpent.assign(vout.size(), fSpent);
-        }
 
-        if (fRead)
             ReadOrderPos(pthis->nOrderPos, pthis->mapValue);
 
+            pthis->nTimeSmart = mapValue.count("timesmart") ? (unsigned int)atoi64(pthis->mapValue["timesmart"]) : 0;
+        }
+
         pthis->mapValue.erase("fromaccount");
         pthis->mapValue.erase("version");
         pthis->mapValue.erase("spent");
         pthis->mapValue.erase("n");
+        pthis->mapValue.erase("timesmart");
     )
 
     // marks certain txout's as spent